The purpose of this study was to assess patients' attitudes to and experiences of participating in the clinical training of medical students. Samples of patients (n = 582) selected at random from six different departments (gynaecology, psychiatry, internal medicine, paediatrics, urology and a health care centre with general practitioners) were interviewed by means of a questionnaire. The patients were selected from those who had consulted the actual departments in the last six months of 1995. Four hundred and forty-one patients (76%) answered the questionnaire. Seventy-one per cent of all patients had experience of participating; of these 41% had estimated that they had once or several times participated without being informed. Eighty per cent felt aggrieved if they were not informed. On average 88% were, in principle, positive to participating. Of those who were, in principle, negative a majority had negative experiences of participating. Elderly patients tended to accept participating more often without being informed. Almost all patients seemed to be positive to participating in the education of medical students, although a silent precondition might be that patients should be informed and given the opportunity to abstain.